Integrated Pest Management Program Department of Plant Science and Landscape Architecture

UConn Extension

Greenhouse Integrated Pest Management

What is Integrated Pest Management?

Integrated Pest Management (IPM) is a holistic approach to managing insects, diseases, weeds and cultural problems in the greenhouse. It is the use of a variety of different pest management tactics including cultural, biological, physical, mechanical, and chemical controls. Frequently, two tactics, such as cultural and biological controls, are combined to ensure a successful pest management program. Pest management decision making is based upon information gathered from a regular monitoring program. Weekly, regular inspection of plants enables you to detect potential problems early before they develop into serious problems.

Some of the components of a Greenhouse IPM program include:

1. Initial information gathering on the identification and life history of key pests and biological control agents

2. Establishment of a regular monitoring program for key pests and biological control agents

3. Determination of a tolerance level for pest activity

4. Development of a record keeping system

5. Pest management decision. Your decision may be to control the pest, not to control the pest (because it is below your tolerance level) or to continue to monitor.

6. After a treatment is made, evaluate the effectiveness of your treatment.

Prevention

Before introducing a crop, evaluate the entire greenhouse for the presence of potential problems. Note the presence of “pet plants”, weeds, algae, and growing media debris especially underneath benches, because these provide a refuge for many greenhouse pests. Prevention of pests is easier if you identify, analyze and correct existing problems before plants are introduced.

Many insects and diseases can be accidentally introduced into a greenhouse when infested cuttings, plugs, or plants are introduced. Inspect incoming plant material for the presence of insects and diseases and evaluate their general plant health and quality, as well. If feasible, isolate infested plants in a separate greenhouse or growing area.

Cultural Controls and Sanitation

Providing proper cultural controls for the crops you are growing is the key to a successful IPM program. By providing the proper environmental conditions (light, water, temperature and nutritional levels), you can insure high quality crops.

Regular monitoring of electrical conductivity (EC) and pH of the growing media will help develop a successful nutritional program. Over fertilization of plants, especially with nitrogen, encourages the development of aphids, whiteflies, mealybugs and spider mites. The resulting lush plant growth is more susceptible to foliar diseases such as Botrytis blight and Rhizoctonia web blight.

Figure 1: Regular use of meters to measure EC levels. Photo by L. Pundt

High soluble salt levels and the incorrect pH can encourage Pythium root and stem rot.

Overwatering encourages the development of Pythium and other root rot diseases.

A clean greenhouse helps to prevent many potential pest problems.

Keeping the walkways and areas under the benches free of spilled potting media, weeds and debris can help prevent many insect and disease outbreaks.

Disinfecting benches and walkways between crops will help to minimize disease spread.

Figure 2: A clean, disinfected greenhouse between crops will prevent many pest and disease problems. Photo by L. Pundt

Discard heavily infested plants into garbage containers with tight sealing lids to prevent winged insect pests from migrating back into the crop.

Keeping the hose ends off the floor will help prevent many root and stem diseases.

The cull pile should be kept as far from the greenhouse as possible in order to discourage reentry of winged insect pests and disease spores.

Proper spacing of plants will promote healthy growth and discourage the development of foliar diseases such as Botrytis blight.

Disease suppressive mixes and biological fungicides are being used successfully by many growers.

Growers are more likely to be successful in using biological controls if they are integrated with proper cultural controls and a regular, consistent monitoring program.

Initial Information

Gathering information on the biology and life history of key pests and biological control agents is critical to insure effective decision making. Proper identification of insects, diseases, weeds and cultural problems is critical to insure that effective management tactics are employed.

Developing a Monitoring Program

By thorough, consistent scouting, you can detect potential problems early and gather current information on the identity, location and causes of pest problems. Consistent scouting will also enable you to evaluate the effectiveness of the biological control agents released. In Connecticut, the Greenhouse IPM program focuses on intensive hands-on educational training and site visits throughout the season. The goal is to provide growers with the knowledge, skills, experience and confidence needed to achieve effective implementation of IPM.

Who Should Scout?

Scouting may be done in-house or by private consultants.

Some of the advantages of in-house monitoring include:

Familiarity with the greenhouse and its crop production practices;

Ability to promptly inspect incoming plant material;

Scouting must be considered a high priority by management to ensure inspections on a weekly or as needed basis.

Adequate time and personnel need to be assigned this important activity to insure that other, more routine greenhouse tasks do not interfere with scouting.

Growers may also hire private pest management consultants. Some of the advantages of private consultants include:

Ability to scout quickly and efficiently;

Specialized up-to-date knowledge of pest management.

Some Useful Scouting Tools

Trained employees

10x to 20x hand lens or adjustable headband-mounted magnifier (Optivisor™)

2 x 4 inch magnifying glass

Sticky cards, clothespins and bamboo stakes to monitor winged adult insects

Potato chunks or 1/4 of a potato to monitor fungus gnat larvae

Flagging tape or colored flag to mark pest infested indicator plants

Electrical conductivity (EC) and pH monitoring meters

Record keeping system including scouting forms

Resources to aid in identification of pest insect and mites, biological control agents, diseases and cultural problems

Figure 3: Using a hand lens to monitor for spider mites. Photo by L. Pundt

How to Scout

A monitoring program consists of the use of sticky cards and random plant inspections and the selection of pest-infested plants to be used as indicator plants. Petunias or fava beans can also be used as indicator plants to monitor for the presence of thrips carrying tospoviruses (impatiens necrotic spot virus. (INSV) or tomato spotted wilt virus (TSWV)). You may adapt the following suggestions to your individual greenhouse.

Using Sticky Cards

Use yellow sticky cards to detect infestations of adult whiteflies, fungus gnats, leafminers, shore flies thrips and winged aphids.

Place at the minimum rate of one card per 1,000 square feet.

Space the cards equally throughout the entire range in a grid pattern.

Place additional cards near entrances and vents to detect insect migration from the outside.

Check and change the cards weekly to detect pest population trends.

Record the approximate numbers of adult whiteflies, leafminers, thrips, aphids, fungus gnats and shore flies in additional to any other insects caught on the cards.

It is often helpful to graph data to look at trends and to determine if population levels are increasing or decreasing.

Over time, you can correlate the number of insects found on the cards to the pest damage on the crops to develop your own tolerance level for pest activity.

Figure 4: Use of sticky cards. Photo by L. Pundt

Using Potato Disks

Potato disks are used to monitor for fungus gnat larvae. They can also be used before and after treatments for fungus gnats to evaluate treatment effectiveness.

Gently press potato discs (1 inch in diameter and ¼ to ½ inch in thickness) into the surface of the growing media.

Use 5 to 10 potato discs per 1000 sq. ft. of growing area. Place flagging tape by the potatoes so you can easily locate them.

After two days, check the media surface under the potatoes and the surface of the cut potato for the presence of fungus gnats.

For plug trays, cut the potatoes into a “French-fry” shape and insert into the growing media.

Figure 5: Use of potato discs to monitor for fungus gnat larvae. Photo by L. Pundt

Scouting Route in the Greenhouse

Many insect pests, including whiteflies and spider mites, tend to be densely aggregated. Therefore, random plant inspection is needed to locate the various infestations.

Based upon your past experiences, focus on inspecting those species or cultivars that are more prone to insect, and mite infestations as well as diseases.

For each area of 4,000 square feet, samples should be taken from at least five to ten random sites.

Moving in an "M", or zigzag shaped pattern provides good sampling coverage.

Closely inspect potential problem areas, such as the middle of the bench which may have received less spray coverage or the ends of the benches where there may be less air circulation.

Inspect hanging baskets and any crops grown on the floor.

While scouting, note the presence of diseased plants or weeds to be removed, or any cultural or environmental controls that need to be implemented.

Select and tag pest-infested plants to be used as indicator plants to track population development and evaluate treatment effectiveness.

Plant Inspection

When visually inspecting plants, first consider their general health and vigor.

Closely examine plants that show unusual growth patterns or appear to be under stress.

Inspect leaves, stems and roots.

Closely examine roots to look for signs of root decay or fungus gnat feeding. Healthy roots should be white and actively growing.

Record Keeping System

Develop a record keeping system that will aid in effective decision making.

Keep records of sticky card counts, weekly monitoring, treatments applied and treatment effectiveness.

Specific forms or a small notebook may be used.

Making graphs of population trends helps in decision making.

Keep complete records of the product name of the pesticide used, the product's EPA registration number, the total amount applied, and the size of the area treated, the crop on which the pesticide was applied, and the date and location of the application.

USDA Pesticide Record Keeping Form for Private Applicators

If releasing biological control agents, keep records of the number, type and where the biological control agents were released.

Pest Management Decision Making

Each week, the grower and scout should review the scouting information gathered from sticky card counts, plant inspections, and data from indicator plants. This data will help prioritize a strategy. Looking at trends over a period of time will help decide if controls are needed.

By Leanne Pundt, UConn Extension. 2011, Revised December 2016

References:

Casey, C. Ed. 1997. Integrated Pest Management for Bedding Plants. A Scouting and Pest Management Guide. Cornell Cooperative Extension Publication No. 407. 109 pp. Available online at

Cloyd, R. 2007. Plant Protection. Managing Greenhouse Insect and Mite Pests. Ball Publishing. Batavia, IL. 88 pp.

Daughtrey, M. & A. R. Chase. 1992. Ball Field Guide to Diseases of Greenhouse Ornamentals. Ball Publishing, Batavia, Ill. 218 pp.

Dreistadt, S.H. 2001. Integrated pest management for floriculture and nurseries. University of California Statewide Integrated Pest Management Project, Division of Agriculture and Natural Resources. Publication 3402.

Gill, S. and J. Sanderson. 1998. Ball identification guide to greenhouse pests and beneficials. Ball Publishing. Batavia, IL.

Pundt, L. 1997. New England Integrated Pest Management Scouting Guide for Poinsettias: A Manual for Growers and Scouts. University of Connecticut Cooperative Extension System. 30 pp.

Stack, Lois Berg. (Editor). New England Greenhouse Floriculture Guide. A Management Guide for Insects, Diseases, Weeds and Growth Regulators. New England Floriculture Inc. and the New England State Universities. Available from: Northeast Greenhouse Conference and Expo or UConn CAHNR Communications Resource Center Smith, T. 2015. Cleaning and Disinfecting the Greenhouse. UMass Extension Fact Sheet. Smith, T., and L. Pundt. New England Greenhouse Update. A pest identification website provides photos and descriptions of hundreds of plant problems caused by insects, mites, diseases, nutritional disorders and cultural procedures.

Thomas, C. 2005. Greenhouse IPM with an Emphasis on Biocontrol. Publication No. AGRS-96. 89 pp. Pennsylvania Integrated Pest Management Program.

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